Tamping bar clamp



Jan. 2, 1940. v o. TUERCK TA'MPING-BAR CLAMP 3 Sheets-Sheet 1 Filed Nov. 50, 1938 Fig. 1

Inventor Oscar Tuerc/r IT. BY all Jan. 2, 1940.

o, TUERCK TAMP ING -BAR CLAMP Filed Nov. 30, 1938 3 Sheets-Sheet 2 A h Mm Fig 8 k 2 5 w m mp M 1m mn Mn T Jan. 2, 1940. o; TUERCK 2,185,613

TAMPING-BAR CLAMP Filed Nov. 30, 1938 3 Sheets-Sheet 3 Fig. 5

11 I8. a? ,ae Fig.6

Inventor I 0 F1 8 scar 'TZJGICJI Patented Jan. 2, 1940 1 TAMPING BAR CLAMP Oscar Tuerck, Portland, reg., assignor to Tuerck Mackenzie Company, Portland, 0reg., a corporation of Oregon UNITED. STATES PATENT OFFICE I EApplication November 30, 1938, Serial No. 243,195 I 11 Claims; ((71.25-37) This invention relates to a tamping device, and, the clamping mechanism in the manner heremore specifically, to tamping apparatus used in inafter described with reference to the accommachines for making concrete-pipe and'the like. panying drawings, wherein In concrete-pipe machines, such for example, Fig. l is an assembly view of a concretapipeas the concrete pipe machine shown in United making machine, the tamping mechanismbeing States Letters Patent No. 1,532,937, issued Janshown in full line and the remainder of the uary 20, 1925, to which reference is made, it is machine in broken line;

necessary to have suitable means for tamp-ing Fig. 2 is a, transverse section taken on line the concrete mixture as it is fed into the pip of l, but dYaWnOIl rger S a e;

m mold. {Such means, in concrete-pipe machines Fig. 3 is a front elevation of my improved 0. of the type referred'to, customarily comprises tamping-bar friction clamp; one or more tamping bars clamped to a suitable Fig. 4 is a vertical medial section taken on 4 reciprocating mechanism. line 4-4 of Fig. 3;

The clamp by which the tamping bar or bars Fig. 5 is a detail planview of my improved are attached to the reciprocating" inechanisn'lv means for variablyadjusting and for rapidly set must'be-so arranged and constructed that suftingxor releasing the frictional engagement of ficient tamping force will'be imparted to the the'clamp with the tamping bars;

tampingn bars and still permit of gradual up Fig. 6 is a corresponding medial section. taken ward slippage of the tamping bars" through the on line 66 of Fig. 5; 1 I clamp asthe material or concretemixture rises Fig. '7 is'a transverse section taken on line 20 Within the mold. Furthermore, when one mold !'l of Fig, 6 and illustrating, an important dehas been filled, and is replaced by an empty tail of construction; and.

mold, the tamping bars must be released and Fig. 8 is a .plan view of the cam-operated.

returnedto their original-position in order to thruster shown removed fromthe structure ilstart the tamping operation again. l'ustrated in Fig. 5. 25

n bj c Of this invention p v d an vIn concrete-pipe-fabricating machines of the improved t'amping-bar clamp which will facilitype illustrated in Fig. 1,- the entire apparatus tate the'releasing of the tamping-bars whenever .for tamp-ing the moist concrete, as it is deposthis is desired, and similarly will facilitate the. ited in the space between the stationary core clamping of the bars again subsequent to such and rotating jacketof the pipe mold, is cus- 30 releaml. v tomarily carried on swinging brackets such as 'Anothercbject of this invention is to provide a and I) mounted on the standard c of the maa clamp of this type with which the clamping chine frame, these brackets a and 72 being shown force'may be easily increased or decreased within full line in Fig. l. A frame d, which is see out interrupting the "tamping operation and cured to the swinging brackets on and b, is pro 35 Without necessitating any sing or adju t ng vided with an integral boss e and with sleeve of t p ng-bars or associated parts. blocks 1 and g disposed above and below the A further object of this invention is to provide boss. The boss e serves as a journal for the a tamping-bar clamp which can be adjusted, for shaft h which is also, supported by other bear- 40 tamping-bars of different thickness, and can be ings such as i mounted on the bracket a, and 4,0

I adjusted so as to compensate for wear on'the the shaft h is driven by an electric motor :i

tamping bars or shoes associated therewith. through the media of suitable power transmit- An' additional object of this invention is to ting means as for example the belt drive shown. provide an adjustable clamp whichwill not 1 The usual eccentric wheel kis'keyed to the work; loose whilethe tamping machine is in opforwardly extending end of the driven shaft n, 45

eration and will not become less; efficient due to v and a connecting rod Z, rotatably mounted at vordinarywear of any of the parts. one end on a pin made fast in an eccentric posi- A 'stillfurth'er object's toprovide mama tion on the wheel 70 and at the other end on a bar clampdesignedto meet the'above requirestub shaft integral with the housing ll! of the 'ments which will, nevertheless, be simple in. contamping-bar clamp n, serves to convert and 50 structionand inexpensive to manufacture. These transmitthe rotary motion of 'the wheel 70 to and incidental objects are attained by making vertically reciprocating movement of the tampthe clamping device with a cam lever and with ing-bar clamp 11. in the "manner customary in: an adjustable screw socket, and, furthermore, concrete-pipemaking machines;

5; by constructing and mounting the membersof A pair of bars 0 and p, slidably disposed'in the only one such reinforcing element, my improved friction clamp has been shown in the drawings and will be presently described as applied to the usual pair of tamping bars, these bars being designated 8 and t, it being understood that my improved clamp may be used with any number v of tamping bars, or with only a single tamping bar. The tamping bars, which are customarily made of hardwood and have metal shoes secured to their lower extremities, extend through the housing N3 of the friction clampn (see Figs. 2 and'4).

The clamp n is equipped with the usual friction shoes 1) and w and with the spacer .r, substantially as shown in Fig. 4. These friction elements are preferably provided with leather covering on the surfaces engaging the tamping'bars and are loosely disposed in the box-like housing ll! of the clamp 11. Pressure brought to bear on a leaf spring y, disposed in the housing 18 and operative on the friction shoe 0, forces the shoes 1: and w and the spacer .r'into frictional engagement with the interposed tamping bars.

The housing in of the clamp n is provided with a central integral boss H! which is internally threaded to receive the externally threaded portion it of an adjusting screw generally designated l2 and shown in detail in Figs. 5 and 6.

The outwardly extending end portion of the adjusting screw i2 is bifurcated to form a yoke for the disk-like cam head l3 of a lever M which is mounted for arcuate movement on a pin l5 disposed in the bifurcated end of the yoke so as to be eccentric with respect to the substantially circular cam portion l3 of the lever 14 as seen,

in Fig. 6. A counterbalance l6, of suitable proportions, is formed, integrally with or firmly secured to the cam i3 and is disposed on the periphery thereof in such manner as to enhance the tendency of the lever I l to gravitate to the pressure-applying position shown in the several figures and, in addition, to partially counteract the weight of the outstanding lever I 4 when the adjusting screw is rotated to positions such as those shown in broken outline in Fig. 3. This latter function of the counterbalance l6 will be more fully explained later. The cam 13 isprovided with a peripheral groove l1 extending almost half way around the earn from a point adjacent the counterbalance it to a shoulder l1 (Fig. 6) which incidentally functions as a stop to limit the arcuate downward movement of the lever arm M. The body of the adjusting screw i2 is formed with a concentric bore in which is reciprocably disposed a substantially cylindrical thruster or cam follower! 8 (shown isolated in Fig. 8), one

end of which is bifurcated to receive a roller IS. The roller i9 is mounted on a fixed pin 28 and adapted to traverse the cam groove 11 and affords rolling contact between the cam and the thruster. A semi-spherical or other projection 2| formed on the opposite end of the thruster l8 registers with a central hole provided in the leaf spring compress the leaf spring 3 against the friction Y shoe 1). The amount of pressure thus exerted onthe leaf spring will dependon the position of the adjusting screw l2 in the boss ill. But the position of the adjusting screw l2 J may readily, be varied byscrewing it toward or away from thelleaf spring y. using the lever M as an aid in rotating the screw. This action is illustrated-by I the broken lines in Fig. 3.

While the-externalthreads of the adjusting screw l2 are made a reasonably tight fit in the internal threads of the boss l0, frequent adjustment of the screw l2 would eventually'wear the threads somewhat and result in a slack fit. In order to maintain the proper fit of the adjusting screw 12 in the boss illand so prolong the eflie cient working life of the clamping mechanism'I provide the threaded portion of the adjusting screw l2 with a plurality of longitudinal slots 22; preferably three, as shown in Fig. 7, these slots 22 divide the threaded portion H of the adjusta ing screw into three similar sections which are made with a tendency to expand radially. Thus a proper fit ofthe slotted threaded portion is assured in spite of any threads. I

The operation of my clamp may nowbe described with particular reference to Fig. 2. As the moist concrete materials accumulate in the pipe mold'in the space between the stationary core A and the rotating jacket B, it is necessary to permit the tamping'bars s and t, which are being reciprocated by the motor-driven eccentric wheel k and mechanism heretofore described,

gradual wear of the screw radually to be pushed upward in the friction:

clamp n at a rate approximately equal to the rate of rise of the materialsin the mold.

When the mold has been completely filled'fthe motor actuating the tamping bars is shut 011*," the core Ais raised above the jacket B, the jacket B containing the molded pipe is moved away, and replaced by an empty jacket whereupon 'the core A is dropped down again into place, there inforcement placed in the mold, and the eoncrete or moist mixture is again ,fedin'to the mold;

The tamping bars are then quickly released *permitting them to drop down into the mold, and are again clamped, while the motor reciprocating the clamping bars starts operating. It is obvious that, with the use of my clamp, all that it is necessary for the operator to do, in orderto .drop the: tamping bars into place and secure them, is to;

move the lever handle !4 into the position shown bythe broken line in Fig. '6, which immediately permits the tamping bars to drop to the bottom 1 of the mold, and then return'the lever handle [4 to the normal clamping position. This requires considerably less effort and time thanis required."

for example, with the ordinary screwclamp such.

as that illustrated in United States Patent No. l

Furthermore;

1,523,937, previously referred to.' when my clamp is released and again clamped, during the changing of the mold there is no. disturbance of the adjustment of the clamp, and

consequently the operator is assured of obtaining the same clamping pressure on the tamping bars; This is very important, since too muchor too little clamping pressure would greatly influence the tamping force exerted by the machine.

It is a well-known fact, however, that it is difiicult to: obtain exact uniformity in the proportions and moisture-content of the mixture fed into the pipe mold, and consequently it is necessary to make occasional adjustments in the tamp ing'force in order to maintain the density of. the tamped material in'the pipe as constant as possible. The ear of the experienced operator can detect slight changes in density from variations in the sound made by the impact of the tamping bars with the material. The operator then tightens or loosens the clamp slightly in order to obtain greater or less tamping force. With my clamp this is done very easily merely by pushing the lever slightly either clockwise or counter clockwise, as the case may be, for example into one of the positions illustrated by the broken lines in Fig. 3. It is not even necessary to stop the action of the tamping bars in order to obtain this adjustment in the tamping force exerted. The constant, reasonably tight fit of the cooperating screw threads on the screw 12 and in the boss l0, together with the counter-balancing sheet of the counter-weight l6,:will sustain the screw and hand lever in such adjusted position. and, of course, the hand lever I4 can be actuated to release the tamping bars and re-clamp them,

at the time of the changing of themold just as easily as when the hand lever swings in a ver tical plane.

It would, of course, be possible to make minor changes in the form and construction of the cam, hand lever, and thruster without departing from the principle of my invention. It is not my intention to limit my invention otherwise than as stated in the accompanying claims.

I claim:

1. In a tamping device of the character described, a tamping bar clamp including a housing, a spring within said housing, means for. applying tension to said spring comprising, an adjusting screw extending into said housing, a concentric bore extending thru said screw, a thruster element slidable within said bore, the inner end of said'thruster bearing against said spring, a cam lever pivotally mounted in the outer end of said screw and bearing against the outer end of said thruster, whereby. when said lever is moved into one position, said thruster will be caused to compress said spring.

2. In a clamp of the character described, a housing, a spring within said housing, means for applying tension to said spring comprising an adjusting screw extending into said housing, an aperture extending longitudinally thru said screw, a thruster element slidable within said aperture, the inner end of said thruster bearing against said spring, a cam lever pivotally mounted in the outer end of said screw and. bearing against the outer end of said thruster, whereby, when said lever is moved into one position, said thruster will. be caused to compress said spring, a counter balance on said cam lever, said counter-balance adapted to reduce the tendency of said lever to cause said screw to turn when said lever is moved out of a vertical plane.

3. A tamping bar clamp comprising a housing, friction shoes supported by said housing, a spring within said housing adapted to. apply tension to said friction shoes, an adjusting screw extending into said housing, a concentric bore. extending thru said screw, a thruster element slidable within said bore, the inner end of said thruster bearing'against said spring, a cam lever pivotally mounted inthe outer end of said screw and hearing against'the outer end of said thruster, whereby,'wh-en said lever is moved into one position, said thruster will be caused to compress said spring, the threaded portion of said screw having a plurality of longitudinal slots to permit the radial expansion of said screw and thereby maintain a tight fit of said screw.

4:. In' a tamping'd'evic'e of the character described, including a pair of tamping bars, a tarr'iping bar clamp including a housing, said tamping bars extending thru said housing, a spacer in said housing between said tamping bars, friction producing means within said housing, means for applying tension to said friction producing means comprising an adjusting screw extending into said housing, an aperture extending longitudinally thru said screw, a thruster element slidable within said aperture, the inner end of said thruster bearing against said friction producing means, a cam lever pivotally mounted in the outer end of said screw and bearing against the outer end or" said thruster, whereby, when said lever is moved into one position, said thruster will be caused to press against said friction producing means.

5. The combination described by claim 4 including a counter-balance on said cam lever, said counter-balance adapted to reduce the tendency of said lever to cause said screw to turn when said lever is moved out of a vertical plane.

6. The combination described by claim 4 with the threaded portion of said screw having a plurality of longitudinal slots to permit the radial expansion of said screw and thereby maintain a tight fit of said screw.

'7. In a clamp of the character described, a housing, friction producing means within said housing, a thruster element extending thru'one wall of said housing, the inner end of said thrustor bearing against said friction producing means, a cam lever located outside of said housing and bearing against the outer end of said thruster, whereby, when said lever is moved into one position, said thruster will be caused to press against said friction producing means, a counterbalance on said cam lever adapted to maintain said cam in pressure applying position.

8. In a tamping device of the character described, a housing, friction shoes supported by said housing, a spring within said housing adapted to apply tension to said friction shoes, an adjusting screw extending into said housing, an aperture extending longitudinally thru said'screw, a thruster element slidable within said aperture, the inner end of saidthruster bearing against said springeam means associated with the outer end of said adjusting screw and adapted to force said thruster inwardly, means for retaining said cam means in pressure applying position.

9. The combination described by claim 8 with the threaded portion of said screw having a plurality of longitudinal slots to permit the radial expansion of said screw and thereby maintain a tight fit of said screw.

10. In a clamp of the character described, a housing, an adjusting screw extending into said housing, an aperture extending longitudinally thru said screw, a thruster element slidable within said aperture, cam means associated with the outer end of said adjusting screw and adapted to force said thruster inwardly, a hand lever attached to said cam means, the threaded portion of said screw having a pluralityjof longitudinal slots to permit the radial expansion of said screw and thereby maintain a tight fit of said screw, a counter-balance on said cam lever, said counter-balance adapted to reduce the tendency of said lever to cause said screw to turn when said lever is moved out of a vertical plane.

11. In a tamping device of the character described, including a pair of tamping bars, a hous ing, said tamping bars extending thru said housing, a spacer in said housing between said tamping bars, friction shoes supported by said housing, means for adjusting the frictional engagement of said shoes with said tamping bars, said means including a slidably mounted thruster element,

said manually operated means with respectl to said housing.

OSCAR TUERCK. 

